“Many gregarious tropical species are shifting poleward under current ocean warming and interacting in new ways with fish in more temperate areas.”

The scientists investigated how fish species interacted and behaved when water temperatures and acidification changed under controlled laboratory conditions. When coordinating together in a shoal after being spooked by predators, tropical and temperate fish species usually tend to move to the right. However, this bias significantly diminished in conditions when ocean acidification levels were higher.

“Mixed shoals of tropical and temperate species became less cohesive under future climate conditions and showed slower escape responses from potential threats,” explained study co-author Angus Mitchell, a doctoral student at the University of Adelaide who performed the laboratory experiments.